Securities represented by a check or a bill are widely used as a means to settle accounts with money by a means other than cash. Such securities have a value equivalent to the par value or the amount of money written thereon and are generally considered to be easily portable and excellent in security compared to carrying cash.
However, it may occur that a person with malicious intent uses illegal securities if securities can be easily forged and/or tampered with. For this reason, it is preferably considered that securities are provided with forgery and tampering prevention treatments by a variety of techniques.
As an example of a forgery prevention treatment, a treatment is provided in which the variable information such as the number to distinguish the kind of the cash or the bill, the number of the clearinghouse, the number of the financial institution, the number of the branch, the account number of the drawer, and the serial number of the check or the bill is printed at the bottom of checks or bills which are securities, and thus each item of the securities can be identified by the numbers. The variable information can be easily read visually under natural light.
In addition, the variable information can also be read as a magnetic waveform using a specific reading device by providing securities with a treatment such as setting the size and shape of each information to a fixed form; and printing the information with a magnetic ink having unique magnetic properties. It may be difficult to determine the authenticity of the securities which have only been subjected to the former treatment by visual inspection even in a case in which the securities have been forged using a general copier or printer. However, the presence or absence of forgery can be more easily determined using a specific reading device when the latter treatment has been performed.
Meanwhile, the printing process at the time of producing securities can be divided into two steps when roughly classified. In other words, the printing process is divided into a step of printing regulatory information to print a regulated character, pattern, or the like using a printing plate and a step of printing variable information to print variable information as described above without using a printing plate but by electrical signals sent from a computer.
An offset printing system having a fast printing speed has been mainly used in the step of printing regulatory information, and a digital printing system represented by an electrophotographic system or an inkjet system has been mainly used in the step of printing variable information in many cases.
In the digital printing system represented by an electrophotographic system or an inkjet system, a printing plate is not required; and it is possible to change freely the print information according to the print signal sent from a computer, or the like, and thus the digital printing system is a printing system suitable for the variable information printing or the small lot multi-item printing.
Since the digital printing system does not require a printing plate, the digital printing system does not require the cost required to create a new printing plate according to the design of the matter to be printed; labor required to replace and position the printing plate; a large amount of waste paper generated in the process for adjusting the printing conditions; or the like as well. For the reason described above, as a result, the printing often can be performed by the digital printing system at lower cost and in shorter delivery time than the offset printing system in a case in which small lot multi-item printing is performed.
In recent years, the printing speed and the printing precision of the inkjet printing have been remarkably improved, and thus the performance of the inkjet printing can be obtained at the level equal to that of the offset printing in terms of these respects. In addition, the demand on the market for a printed article tends to be small lot multi-item printing, and thus inkjet printing has started to be applied to the part of regulatory information that has been printed by the offset printing of the related art as well in some cases. By virtue of this, the two printing steps of printing the regulatory information and the variable information that have been performed in a combination of the offset printing of the related art and the inkjet printing can be performed by the inkjet printing on its own, and thus an increase in efficiency is expected.
In addition, there are some cases in which the amount of money is written on the securities such as a check or a bill using a stamp or the like in advance, but it is also general that the holder in due course writes the amount of money or the signature on the securities using a writing instrument such as a fountain pen, a ballpoint pen, or a magic pen. Various kinds of organic solvents, a correcting fluid, or the like are used in many cases when a person with malicious intent attempts to tamper with the information written on such securities.
Hence, it is important not to allow unauthorized use by providing securities with a treatment to prevent forgery as well as a treatment to facilitate tampering detection.
As the tampering detection method, a method using a fluorescent dye, an organic solvent-soluble dye, or the like has been proposed. For example, techniques of Patent Documents 1 to 3 are disclosed.
However, it is impossible to detect tampering by visual inspection in the case of using a fluorescent dye, and thus it is necessary to use a special light source. On the other hand, there is an advantage that tampering can be easily confirmed by visual inspection under natural light or normal lighting in the case of using an organic solvent-soluble dye.
However, there is a problem that the presence or absence of tampering cannot be clearly detected since the sheet or the like used in securities having a tampering detection function of the related art is discolored by bleed out caused by the configuration of the sheet itself or color development associated with heating.
In addition, as the means to resolve these problems, a method has also been proposed in which a dye or pigment soluble in an organic solvent is internally added to the paper in advance when the paper to be used for securities or the like is manufactured. However, there is a problem that this method requires extensive labor, and thus the production cost of the paper increases.
Moreover, the safety of chemical substances with regard to the environment or a human being has been highly considered in recent years, and thus improvement is strongly desired from this point of view as well. Among securities, there are also some securities that are frequently used in daily life instead of money. Securities having high safety are required since the contact of the securities with a human being constantly occurs in such a form of use of securities or the like.
A dye or a pigment soluble in an organic solvent is generally classified into a disperse dye or an oil-soluble dye. However, some disperse dyes or oil-soluble dyes are known to be harmful to the human body, and thus a contrivance is required which prevents the securities from being directly touched by the skin of a human being by, for example, over-coating the dye with a binder resin or the like, or minimizes the part being touched by the skin of a human being by internally adding the dye to the paper when such dyes are used. However, a contrivance is hardly a fundamental solution from the viewpoint of safety as well as there is a great problem that such a contrivance is technically complicated and leads to a cost increase. For this reason, a method is strongly desired which leads to low cost, exhibits high safety with regard to the environment or particularly a human being, and enables tampering to be easily detected.    Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2000-129596    Patent Document 2: Japanese Unexamined Patent Application, Publication No. 2008-31594    Patent Document 3: Japanese Unexamined Patent Application, Publication No. 2011-149107